REPOET ON THE MONAXONIDA. xvii 



simply rounded off at the other it is said to be cladostrongylote, and the sj)icules are 

 cladostrongyla. Such spicules occur in Thrinacopliora funiformis, nobis {vide 

 PL XXIII. figs, le, If). 



2. Cladotylota (woodcut, Fig. III., 2); when it is branched at one end and swollen 

 into a knob at the other, it is said to be cladotylote, and the spicules are cladotylota. 

 Such forms occur in the genus Acarnus. 



Any of the above forms of megasclera may become spinose, as frequently happens in 

 the case of styli (e.g., in the genus Myxilla), but this in no way affects their fundamental 

 forms or the names applied to them. 



Swellings, also, may be developed elsewhere than at the ends of the spicule ; hence, 

 when there is a swelling in the centre of the spicule it is said to be centrotylote 

 (PI. IX. fig. 2, h, c), and when there are several swellings on a spicule (no matter where 

 they are situate) it is said to be polytylote (PI. XIX. figs. 9, 9'). 



Microsclera. 



The microsclera of the Monaxonida exhibit considerable variety in form, and it is no 

 easy matter to arrange them satisfactorily in natural groups. The simplest plan, and 

 that which we shall adopt here, is to consider them under three heads — (A) simple 

 linear forms, (B) hooked forms, and (C) stellate forms. This may be an artificial 

 arrangement, but it is a convenient one in practice, and as yet we hardly know enough 

 about the question to allow of a more philosophical classification. 



A. Simple Linear' Forms. 



1. Minute oxea (woodcut. Fig. IV., 3), which are generally if not always spined, as 

 in Dendropsis bidentifera, nobis (PL XL. fig. 7c), Spongilla lacustris, &c. 



5 



Fig. IV. — Linear forms of microsclera. 



2. Ehap>hides (woodcut. Fig. IV., 1) ; long, hair-like spicules, not in sheaves. These 

 occur in great abundance in the genus Tedania. 



(ZOOL. CHAIjL. EXP. PART LIX. — 1887.) ^'^^ '^ 



